/*
 * Copyright (c) 2021 Huawei Device Co., Ltd.
 * Licensed under the Apache License, Version 2.0 (the 'License');
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an 'AS IS' BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
import { Readable, Writable, Duplex, pipeline } from "@ohos/node-polyfill"

const log = (message) => {
    console.log(message)
}

class YReadable extends Readable {
    constructor() {
        super();
        this.arr = [1, 2, 3, 4, 5, 6, 8, 9, 10];
        this.index = 0;
    }
    _read(size) {
        if (this.index > this.arr.length - 1) {
            this.push(null);
            return;
        }
        this.push(this.arr[this.index++] + "");
    }
}

class YWritable extends Writable {
    constructor() {
        super();
        this.dest = [];
    }

    _write(chunk, _, callback) {
        this.dest.push(chunk.toString());
        callback();
    }
}

class YDuplex extends Duplex {
    constructor() {
        super();
        this.source = [];
        this.index = 0;
    }

    _write(chunk, encoding, callback) {
        this.source.push(chunk.toString());
        callback();
    }

    _read() {
        if (this.index > this.source.length - 1) {
            this.push(null);
            return;
        }
        this.push(this.source[this.index++] + "");
    }
}


export function run_stream() {
    log("------ stream demo start ------")

    const readable = new YReadable();
    const writable = new YWritable();
    const duplex = new YDuplex();

    /**
     * pipeline demo
     */
    pipeline(readable, duplex, writable, (err) => {
        if (err) {
            log("Pipeline failed." + err.message);
        } else {
            log("Pipeline succeeded.");
        }
    });

    /**
     * pipe demo
     */
    // readable.pipe(duplex).pipe(writable);

    readable.on("end", () => {
        log("writable.dest----" + writable.dest);
        log("duplex.source----" + duplex.source);
        log("------ stream demo end ------")
    });
}

